Commutator and armature

Abstract

A commutator including a commutator main body having a plurality of commutator pieces and a short-circuit member having a short-circuit conductor for short-circuiting commutator pieces. The short-circuit conductor includes superimposed first and second short-circuit member formation groups. The first short-circuit member formation group is thinner than the second short-circuit member formation group. The first and second short-circuit member formation groups are fixed to each other by crimping projections, which are formed on the second short-circuit member formation group through punching, in a state inserted through holes, which are formed in the second short-circuit member formation group.

1. A commutator comprising:
 a commutator main body including a cylindrical main body insulator and a plurality of commutator pieces held on an outer circumferential surface of the main body insulator so that the commutator pieces are arranged in a circumferential direction of the main body insulator; and 
 a short-circuit member attached to the commutator main body and including a short-circuit conductor that short-circuits the commutator pieces; 
 wherein the short-circuit conductor includes first and second short-circuit member formation groups arranged with one of said first and second short-circuit member formation groups superimposed over the other with respect to a direction of an axis of the commutator, with each of the short-circuit member formation groups having a plurality of outer terminals arranged about the axis of the commutator, a plurality of inner terminals arranged about the axis of the commutator radially inward from the outer terminals, and a plurality of linking portions linking each of the outer terminals to one of the inner terminals, wherein the linking portions in at least one of the first and second short-circuit member formation groups links the outer terminals and the inner terminals that are separated from each other by a predetermined angle in the circumferential direction; 
 wherein each of the outer terminals in the first short-circuit member formation group contacts one of the outer terminals in the second short-circuit member formation group, each of the inner terminals in the first short-circuit member formation group contacts one of the inner terminals in the second short-circuit member formation group, and the linking portions in the first short-circuit member formation group are maintained in non-contact with the linking portions in the second short-circuit member formation group; and 
 wherein the first short-circuit member formation group is thinner than the second short-circuit member formation group with respect to the direction of the axis of the commutator, the second short-circuit member formation group has a plurality of projections formed through punching, the first short-circuit member formation group has a plurality of holes respectively corresponding to the projections, and the first short-circuit member formation group and the second short-circuit member formation group are fixed to each other by crimping the projections in a state inserted through the corresponding holes. 
 
   
   
     2. The commutator according to  claim 1 , wherein the first short-circuit member formation group is formed from a material having a smaller electric resistivity than the second short-circuit member formation group. 
   
   
     3. The commutator according to  claim 2 , wherein the first short-circuit member formation group is formed from a copper material, and the second short-circuit member formation group is formed from a brass material. 
   
   
     4. The commutator according to  claim 1 , wherein the short-circuit member includes a short-circuit insulator for holding the short-circuit conductor in a state embedded in the short-circuit insulator. 
   
   
     5. The commutator according to  claim 4 , wherein the main body insulator and the short-circuit insulator are formed from different materials. 
   
   
     6. The commutator according to  claim 5 , wherein the main body insulator is formed from a thermosetting resin, and the short-circuit insulator is formed from a thermoplastic resin. 
   
   
     7. The commutator according to  claim 1 , wherein the holes have openings opposite the second short-circuit member formation group and include conical inclined surfaces having a diameter that is outwardly enlarged. 
   
   
     8. The commutator according to  claim 7 , wherein the projections are punched out to have a length greater than a plate thickness of the first short-circuit member formation group. 
   
   
     9. The commutator according to  claim 1 , wherein the projections are formed on the outer terminals and the inner terminals in the second short-circuit member formation group, and the holes are formed in the outer terminals and the inner terminals in the first short-circuit member formation group. 
   
   
     10. The commutator according to  claim 1 , wherein at least either one of the linking portions in the first short-circuit member formation group and the linking portions in the second short-circuit member formation group are curved or bent to be spaced from the other one of the linking portions in the first short-circuit member formation group and the linking portions in the second short-circuit member formation group in a superimposing direction of the two short-circuit member formation groups. 
   
   
     11. The commutator according to  claim 1 , wherein the linking portions are thinner than the outer terminals and the inner terminals in at least one of the first short-circuit member formation group and the second short-circuit member formation group. 
   
   
     12. The commutator according to  claim 1 , wherein the short-circuit member is arranged at one axial end of the commutator main body. 
   
   
     13. An armature comprising:
 the commutator according to  claim 1 ; 
 a rotation shaft extending through the axis of the commutator; 
 an armature core fixed to the rotation shaft so as to be axially aligned with the commutator, wherein the armature core has a plurality of teeth; and 
 a plurality of coils wound around the teeth.